VITAMINS

Question 1

Vitamin A fat soluble ?

Answer 1

yes

Question 2

where is Vitamin A stored

Answer 2

Store in ito cells in the space of Disse of the liver

Question 3

function of vitamin A

Answer 3

• Cellular growth & differentiation
• Process of vision (retinal pigments)•Healthy skin
• Reproduction
• Embryonic development
• Maintenance of bodies mucus membranes
• Used in lymphocyte production - immune system

Question 4

Sources of Vitamin A

Answer 4

• Liver
• Dairy products
• Oily fish
• Margarine

Question 5

what happens with Vitamin A deficiency

Answer 5

• Night blindness
• Xerophthalmia (eye fails to produce tears)
• Growth retardation
• Keratinisation of epithelia
• Impaired hearing, taste & smell
• Increased susceptibility to infection

Question 6

What is Vitamin C soluble in

Answer 6

water

Question 7

Functions of Vitamin C

Answer 7

• Synthesis of; collagen, neurotransmitters & carnitine (used in beta-oxidation)
• Antioxidant ability - can donate electrons to radical O2 compounds
• Absorption of non-haem (plant based) iron

Question 8

Sources of Vitamin C

Answer 8

• Citrus fruits
• Green leafy vegetables
• Potatoes
• Kidney

Question 9

What happens with Vitamin C deficiency

Answer 9

• Initial signs are non-specific
• Weakness
• Bleeding gums
• Hyperkeratosis (thickening of outer layer of skin)
• 50 - 100 days without Vitamin C = signs of scurvy

Question 10

What is vitamin B soluble in

Answer 10

Water

Question 11

Function of Vitamin B

Answer 11

•Important in cell metabolism & energy production

Question 12

What is main vitamin B

Answer 12

B12

Question 13

Where is Vitamin B12 found

Answer 13

found in fish, poultry, meat & eggs

Question 14

what happens with vitamin B12 deficiency

Answer 14

Deficiency results in less erythrocyte formation - pernicious anaemia

Question 15

Where is Vitamin B12 absorbed

Answer 15

terminal ileum

Question 16

What is required for the absorption of Vitamin B12

Answer 16

For absorption, intrinsic factor is required which is produced by the parietal cells of the stomach

Question 17

What is vitamin D absorbed in

Answer 17

fat

Question 18

How long can the liver prevent defence of Vitamin D for

Answer 18

Liver storage prevent deficiency for 3-4 months

Question 19

Types of Vitamin D

Answer 19

D2

D3

Question 20

how is D3 formed

Answer 20

Vitamin D3 (cholecalciferol) is formed by the action of ultra-violet (UV) radiation from sunlight on a cholesterol derivative in the skin

Question 21

what is cholecalciferol

Answer 21

Vitamin D3

Question 22

How is Vitamin D2 derived

Answer 22

is derived from plants

Question 23

How is vitamin D metabolised

Answer 23

Its metabolised by the addition of hydroxyl groups, first in the liver and then in certain kidney cells,
the end result of these changes is 1,25-dihydroxyvitamin D (1,25-(OH)2D) - the active hormonal form of vitamin D

Question 24

Functions of 1,25-(OH)2D

Answer 24

Its major action is to stimulateintestinal absorptionof Ca 2+ and phosphate

Question 25

(1) Vitamin D deficiency What first happens if there is a Vitamin D deficiency

Answer 25

* Major consequence is decreased intestinal Ca2+ absorption resulting in a decreased plasma Ca2+ * This decrease in detected via a plasma membrane Ca2+ receptor in the parathyroid glands (embedded in the posterior surface of the thyroid gland)

Question 26

(2) Vitamin D deficiency what happens when the plasma membrane Ca2+ receptor in the parathyroid glands detects decreased plasma Ca2+

Answer 26

Resulting in the parathyroid glands releasing PARATHYROID HORMONE (PTH)which exerts multiple actions that increase extracellular Ca2+ concentration:

Question 27

(3) Vitamin D deficiency what multiple actions are exerted to increase extracellular Ca2+ conc by parathyroid hormone (4)

Answer 27

1. It directly increases the resorption of BONE by osteoclasts, which causes Ca2+ & phosphate ions to move from bone into the extracellular fluid - this can lead to a decrease in bone mass - osteoporosis (higher incidence of bone fractures etc.) 2. It directly stimulates the formation of 1,25-dihydroxyvitamin D which then increases intestinal absorption of Ca2+ & phosphate ions, thus the effect of PTH on the intestines is indirect 3. It directly increases Ca2+ reabsorption in the kidneys, thereby decreasing urinary Ca2+ excretion 4. It directly decreases the reabsorption of phosphate ions in the kidneys thereby increasing its excretion in the urine - this keeps plasma phosphate ions from increasing when PTH causes an increased release of both Ca2+ & phosphate ions from the bone and an increased production of 1,25-dihydroxyvitamin D leading to calcium & phosphate ion absorption in the intestine

Question 28

What is Vitamin E soluble in

Answer 28

Fat

Question 29

Main function of Vitamin E

Answer 29

antioxidant

Question 30

What is Vitamin K soluble in

Answer 30

Fat

Question 31

Main function of vitamin K

Answer 31

Main function is that is is essential for the production of clotting factors (10,9,7 & 2) in the liver